What should be used to prevent fine scratches on the nails?

The correct choice for preventing fine scratches on the nails is the fine buffer. Fine buffers are specifically designed to smooth out the surface of the nail and provide a high-shine finish without causing any damage or leaving behind scratches. They have a finer grit that is less abrasive than other options, making them ideal for achieving a polished look.

Using a fine buffer allows nail technicians to refine the nail surface after filing or shaping, ensuring that the nails appear smooth and shiny. This step is crucial in both manicures and pedicures, as it enhances the overall appearance of the nails and prepares them for polish application.

Other options like medium grit abrasives or coarse grit buffers have more abrasive surfaces and are intended for shaping or removing bulk from the nails. These should be used carefully, as they can easily leave scratches or unevenness if used improperly. A hard file, while useful for trimming nails, does not provide the same level of finishing required to avoid fine scratches. Hence, the fine buffer is the preferred tool for achieving a flawless nail surface.